The ASR training corpus consists of 5,000-hour speech data, including 960-hour native speech from LibriSpeech corpus [1]}, and 4,000-hour non-native private recordings from Bytedance. While the pronunciation scoring data consists of 5,000 English utterances spoken by 250 non-native learners from Speechocean762 http://www.openslr.org/101/. The word pronunciation score in each of them has been labeled by five experts, the median scores were adopted following the score files coming with the database, ranging from 0 to 10. Following the calculation method of previous study [2]}, the averaged inter-rater agreement is 0.726. In addition, linguistic experts in Bytedance collected a small amount of task-related unlabeled data (e.g., a group of Chinese adults are required to read aloud given English prompts). It is used in proposed mixup for word-level augmented data generation. The statistics of pronunciation scoring data is detailed in Table REF .
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